#import "ShgSm4OC.h"

#ifndef GET_ULONG_BE
#define GET_ULONG_BE(n,b,i)                             \
{                                                       \
(n) = ( (unsigned long) (b)[(i)    ] << 24 )        \
| ( (unsigned long) (b)[(i) + 1] << 16 )        \
| ( (unsigned long) (b)[(i) + 2] <<  8 )        \
| ( (unsigned long) (b)[(i) + 3]       );       \
}
#endif

#ifndef PUT_ULONG_BE
#define PUT_ULONG_BE(n,b,i)                             \
{                                                       \
(b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
(b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
(b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
(b)[(i) + 3] = (unsigned char) ( (n)       );       \
}
#endif

#define  SHL(x,n) (((x) & 0xFFFFFFFF) << n)

#define ROTL(x,n) (SHL((x),n) | ((x) >> (32 - n)))

#define SWAP(a,b) { unsigned long t = a; a = b; b = t; t = 0;}

NSInteger sm4_block_size = 16;

typedef unsigned char ShgUnsignedChar;

typedef unsigned long ShgUnsignedLong;

typedef const char ShgConstChar;

typedef int ShgInt;

static const ShgUnsignedLong FK[4] = {0xa3b1bac6,0x56aa3350,0x677d9197,0xb27022dc};

static const ShgUnsignedChar SboxTable[16][16] = {
{0xd6,0x90,0xe9,0xfe,0xcc,0xe1,0x3d,0xb7,0x16,0xb6,0x14,0xc2,0x28,0xfb,0x2c,0x05},
{0x2b,0x67,0x9a,0x76,0x2a,0xbe,0x04,0xc3,0xaa,0x44,0x13,0x26,0x49,0x86,0x06,0x99},
{0x9c,0x42,0x50,0xf4,0x91,0xef,0x98,0x7a,0x33,0x54,0x0b,0x43,0xed,0xcf,0xac,0x62},
{0xe4,0xb3,0x1c,0xa9,0xc9,0x08,0xe8,0x95,0x80,0xdf,0x94,0xfa,0x75,0x8f,0x3f,0xa6},
{0x47,0x07,0xa7,0xfc,0xf3,0x73,0x17,0xba,0x83,0x59,0x3c,0x19,0xe6,0x85,0x4f,0xa8},
{0x68,0x6b,0x81,0xb2,0x71,0x64,0xda,0x8b,0xf8,0xeb,0x0f,0x4b,0x70,0x56,0x9d,0x35},
{0x1e,0x24,0x0e,0x5e,0x63,0x58,0xd1,0xa2,0x25,0x22,0x7c,0x3b,0x01,0x21,0x78,0x87},
{0xd4,0x00,0x46,0x57,0x9f,0xd3,0x27,0x52,0x4c,0x36,0x02,0xe7,0xa0,0xc4,0xc8,0x9e},
{0xea,0xbf,0x8a,0xd2,0x40,0xc7,0x38,0xb5,0xa3,0xf7,0xf2,0xce,0xf9,0x61,0x15,0xa1},
{0xe0,0xae,0x5d,0xa4,0x9b,0x34,0x1a,0x55,0xad,0x93,0x32,0x30,0xf5,0x8c,0xb1,0xe3},
{0x1d,0xf6,0xe2,0x2e,0x82,0x66,0xca,0x60,0xc0,0x29,0x23,0xab,0x0d,0x53,0x4e,0x6f},
{0xd5,0xdb,0x37,0x45,0xde,0xfd,0x8e,0x2f,0x03,0xff,0x6a,0x72,0x6d,0x6c,0x5b,0x51},
{0x8d,0x1b,0xaf,0x92,0xbb,0xdd,0xbc,0x7f,0x11,0xd9,0x5c,0x41,0x1f,0x10,0x5a,0xd8},
{0x0a,0xc1,0x31,0x88,0xa5,0xcd,0x7b,0xbd,0x2d,0x74,0xd0,0x12,0xb8,0xe5,0xb4,0xb0},
{0x89,0x69,0x97,0x4a,0x0c,0x96,0x77,0x7e,0x65,0xb9,0xf1,0x09,0xc5,0x6e,0xc6,0x84},
{0x18,0xf0,0x7d,0xec,0x3a,0xdc,0x4d,0x20,0x79,0xee,0x5f,0x3e,0xd7,0xcb,0x39,0x48}
};

static const ShgUnsignedLong CK[32] = {
0x00070e15,0x1c232a31,0x383f464d,0x545b6269,
0x70777e85,0x8c939aa1,0xa8afb6bd,0xc4cbd2d9,
0xe0e7eef5,0xfc030a11,0x181f262d,0x343b4249,
0x50575e65,0x6c737a81,0x888f969d,0xa4abb2b9,
0xc0c7ced5,0xdce3eaf1,0xf8ff060d,0x141b2229,
0x30373e45,0x4c535a61,0x686f767d,0x848b9299,
0xa0a7aeb5,0xbcc3cad1,0xd8dfe6ed,0xf4fb0209,
0x10171e25,0x2c333a41,0x484f565d,0x646b7279
};

typedef enum : NSUInteger {

Decrypto = 0,//解密
Encrypto = 1,//加密

} ShgCryptoMode;

typedef enum : NSUInteger {

ECB = 0,//ECB模式
CBC = 1,//CBC模式

} ShgCryptoPadingMode;

typedef struct {

int mode;
ShgUnsignedLong sk[32];

}ShgSm4Context;

@implementation ShgSm4OC

/// 国密SM4加密，ECB模式
/// @param aString 需要加密的字符串
/// @param key 加密密钥16位长度
+ (NSData *)sm4Encryto:(NSString *)aString key:(NSString *)key {
if (aString == nil || key == nil) {
    return  nil;
}

if (aString.length == 0 && key.length == 0) {
    return  nil;
}

NSStringEncoding gbkEncoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);

NSData *plainData = [aString dataUsingEncoding:gbkEncoding];

if (plainData == nil) {
    return  nil;
}

if (key.length != sm4_block_size) {
    return nil;
}

//对明文数据进行填充来保证位数是16的倍数
ShgInt plainInDataLength = (ShgInt)plainData.length;

//p是需要填充的数据也是填充的位数
ShgInt p = (ShgInt)(sm4_block_size - plainInDataLength % sm4_block_size);

ShgUnsignedChar plainInChar[plainInDataLength + p];

memcpy(plainInChar, plainData.bytes, plainInDataLength);

//进行数据填充
for (ShgInt i = 0; i < p; i++) {
    plainInChar[plainInDataLength + i] =  p;
}

ShgUnsignedChar cipherOutChar[plainInDataLength + p];

ShgConstChar *utf8Key = [key UTF8String];

size_t len = strlen(utf8Key) + 1;

ShgUnsignedChar sm4Key[len];

memcpy(sm4Key, utf8Key, len);

ShgSm4Context ctx;

[self shgSm4SetKeyEnc:&ctx key:sm4Key];

[self shgSm4CryptoECB:&ctx lenght:plainInDataLength + p input:plainInChar output:cipherOutChar];

NSData *cipherTextData =  [[NSData alloc]initWithBytes:cipherOutChar length:sizeof(cipherOutChar)];

return  cipherTextData;
}

/// 国密SM4解密，ECB模式
/// @param data 需要解密的数据
/// @param key 加密密钥16位长度
+ (NSData *)sm4Decryto:(NSData *)data key:(NSString *)key {
if (data == nil || key == nil) {
    return  nil;
}

if (data.length == 0 && key.length == 0) {
    return  nil;
}

if (key.length != sm4_block_size) {
    return nil;
}

ShgUnsignedChar cipherTextChar[data.length];

memcpy(cipherTextChar, data.bytes, data.length);

//调用解密方法，输出是明文plainOutChar
ShgUnsignedChar plainOutChar[data.length];

ShgConstChar *utf8Key = [key UTF8String];

size_t len = strlen(utf8Key) + 1;

ShgUnsignedChar sm4Key[len];

memcpy(sm4Key, utf8Key, len);

ShgSm4Context context;

[self shgSm4SetKeyDec:&context key:sm4Key];

[self shgSm4CryptoECB:&context lenght:(ShgInt)data.length input:cipherTextChar output:plainOutChar];

//由于明文是填充过的，解密时候要去填充，去填充要在解密后才可以，在解密前是去不了的
//p2是填充的数据，也是填充的长度
ShgInt p2 = plainOutChar[sizeof(plainOutChar) - 1];

//明文的长度
ShgInt outLength = (ShgInt)(data.length - p2);

//去掉填充得到明文
ShgUnsignedChar plainOutWithoutPadding[outLength];

memcpy(plainOutWithoutPadding, plainOutChar, outLength);

//明文转成NSData
NSData *outData = [[NSData alloc]initWithBytes:plainOutWithoutPadding length:sizeof(plainOutWithoutPadding)];

NSStringEncoding gbkEncoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);

NSString *outStr = [[NSString alloc] initWithData:outData encoding:gbkEncoding];

NSLog(@"outStr==%@",outStr);

return  outData;
}

+ (void)shgSm4CryptoECB:(ShgSm4Context *)context lenght:(ShgInt)lenght input:(ShgUnsignedChar *)input output:(ShgUnsignedChar *)output {
while(lenght > 0)
{
    [self shgSm4OneRound:context->sk input:input output:output];
    
    input  += 16;
    
    output += 16;
    
    lenght -= 16;
}
}

+ (void)shgSm4OneRound:(ShgUnsignedLong[32])sk input:(ShgUnsignedChar[16])input output:(ShgUnsignedChar[16])output {
ShgUnsignedLong i = 0;
ShgUnsignedLong ulbuf[36];

memset(ulbuf, 0, sizeof(ulbuf));

GET_ULONG_BE( ulbuf[0], input, 0)

GET_ULONG_BE( ulbuf[1], input, 4)

GET_ULONG_BE( ulbuf[2], input, 8)

GET_ULONG_BE( ulbuf[3], input, 12)

while(i < 32)
{
    ulbuf[i+4] = [self shgSm4F:ulbuf[i] x1:ulbuf[i + 1] x2:ulbuf[i + 2] x3:ulbuf[i + 3] rk:sk[i]];
   
    i++;
}
PUT_ULONG_BE(ulbuf[35],output,0);

PUT_ULONG_BE(ulbuf[34],output,4);

PUT_ULONG_BE(ulbuf[33],output,8);

PUT_ULONG_BE(ulbuf[32],output,12);

}

+ (ShgUnsignedLong)shgSm4F:(ShgUnsignedLong)x0 x1:(ShgUnsignedLong)x1 x2:(ShgUnsignedLong)x2 x3:(ShgUnsignedLong)x3 rk:(ShgUnsignedLong)rk {
return (x0 ^ [self shgSm4Lt:(x1 ^ x2 ^ x3 ^ rk)]);
}

+ (ShgUnsignedLong)shgSm4Lt:(ShgUnsignedLong)ka {
ShgUnsignedLong bb = 0;

ShgUnsignedLong c = 0;

ShgUnsignedLong a[4];

ShgUnsignedLong b[4];

PUT_ULONG_BE(ka,a,0)

b[0] = [self shgSm4Sbox:a[0]];

b[1] = [self shgSm4Sbox:a[1]];

b[2] = [self shgSm4Sbox:a[2]];

b[3] = [self shgSm4Sbox:a[3]];

GET_ULONG_BE(bb,b,0)

c = bb^(ROTL(bb, 2))^(ROTL(bb, 10))^(ROTL(bb, 18))^(ROTL(bb, 24));

return c;
}

+ (void)shgSm4SetKeyEnc:(ShgSm4Context *)context key:(ShgUnsignedChar[16])key {
context->mode = Encrypto;

[self shgSm4SetKey:context->sk key:key];
}

+ (void)shgSm4SetKeyDec:(ShgSm4Context *)context key:(ShgUnsignedChar[16])key {
context->mode = Decrypto;

[self shgSm4SetKey:context->sk key:key];

for(ShgInt i = 0; i < 16; i++)
{
    SWAP(context->sk[i], context->sk[31 - i]);
}
}

+ (void)shgSm4SetKey:(ShgUnsignedLong[32])sk key:(ShgUnsignedChar[16])key {
ShgUnsignedLong MK[4];

ShgUnsignedLong k[36];

GET_ULONG_BE( MK[0], key, 0 );

GET_ULONG_BE( MK[1], key, 4 );

GET_ULONG_BE( MK[2], key, 8 );

GET_ULONG_BE( MK[3], key, 12 );

k[0] = MK[0]^FK[0];

k[1] = MK[1]^FK[1];

k[2] = MK[2]^FK[2];

k[3] = MK[3]^FK[3];

for(ShgUnsignedLong i = 0; i < 32; i++) {
    
    k[i + 4] = k[i] ^ ([self shgSm4CalciRK:(k[i + 1] ^ k[i + 2] ^ k[i + 3] ^ CK[i])]);
    
    sk[i] = k[i + 4];
}
}

+ (ShgUnsignedLong)shgSm4CalciRK:(ShgUnsignedLong)ka {
ShgUnsignedLong bb = 0;

ShgUnsignedLong rk = 0;

ShgUnsignedChar a[4];

ShgUnsignedLong b[4];

PUT_ULONG_BE(ka,a,0)

b[0] = [self shgSm4Sbox:a[0]];

b[1] = [self shgSm4Sbox:a[1]];

b[2] = [self shgSm4Sbox:a[2]];

b[3] = [self shgSm4Sbox:a[3]];

GET_ULONG_BE(bb,b,0)

rk = bb^(ROTL(bb, 13))^(ROTL(bb, 23));

return rk;
}

+ (ShgUnsignedChar)shgSm4Sbox:(ShgUnsignedChar)inch {
ShgUnsignedChar *pTable = (ShgUnsignedChar *)SboxTable;

ShgUnsignedChar retVal = (ShgUnsignedChar)(pTable[inch]);

return retVal;
}

@end
